Indene resin stabilized with an alkyl polyhydroxy spiro indane



Patented Feb. 22, 1949 RESIN STABILIZED WITH AN ALKYL POLYHYDROXY SPIRO INDANE Samuel G. Burroughs, Pittsburgh, Pa., assignor to Pennsylvania Industrial Chemical Corporation, Clairton, Pa., a corporation of Pennsylvania No Drawing. Application January 18, 1945,

Serial No. 573,470

4 Claims.

. 1 This invention relates to improvement in indene resin polymers, and the application herein isfa continuation-in-part of my co-pending application, Serial No. 497,039, filed August 2, 1943, which has become abandoned.

:A property of coumarone-indene resin which detracts from the utility of the resin as an ingredient of coating compositions is its tendency to discolor, or yellow. This discoloration takes place very rapidly when the resin forms or is included in a film, such as a paint or varnish film or a'protective film for concrete. It is induced by oxidation, and the progress of the oxidation and discoloration is greatly accelerated by subjection to light containing ultra-violet rays. This tendency to discolor, or yellow, takes place in spite of the care exercised in making the resin, and the phenomenon occurs in coumarone-indene resins of even the greatest purity and lightest initial color. Thus if a coumarone-indene resin of maximum purity and initially a very light yellow color be spread in an apparently colorless film; such film will show a marked yellowish cast after subjection to bright sunlight for only a few days, and the color development will progress to a stage in which the color of the film is a brownish yellow or a yellowish brown.

Resort to various expedients has beentaken, to inhibit color development in coumarone-indene resin by saturation or partial saturation of the polymeric molecules of the resin. The best known and probably the most efiective method of so doing is by hydrogenatiom Hydrogenation is an expensive procedure, and because it greatly increases the solubility of the resin is practiced chiefly for uses of the resin in which solubility of the resin in aliphatic hydrocarbons is a prime requisite.

Improvement in coumarone-indene resin to inhibit discoloration, or yellowing, thereof, is disclosed and claimed in my companion application, serial No. 573,469, filed January 18, 1945. Whereas the tendency of a pure or commercially pure indene resin to discolor is substantially less than that of coumarone-indene resin, such discoloration does take place in the indene resin in such order as greatly to detract from its value. Pure indene resin is a diflicult material to obtain from coke oven light oil, or even from the drip oil resulting as an incident to-thc manufacture of producer gas, because of the very close distillation ranges of monomeric coumarone and indene. Commercially pure indene resin has of the date hereof acquired, however, a more than academic interest because of the production of commercially pure indene (that is, indene from about 96% to 99% pure) in cyclization processes performed on petroleum oils.

I have discovered thatthe discoloration of a resin composed wholly of indene polymers, or of a commercially pure indene resin, like the discoloration of a coumarone-indene resin composed in substantial proportion of coumarone polymers as well as indene polymers, may be rendered negligible by including with the indene polymers an anti-oxidant of special kind. This is true whether the indene polymers stand alone, or whether they be associated with other ingredients of film-forming compositions, adhesives, elastic or plastic bodies, and the like. There is a substantial number of anti-oxidants currently used to prevent, i. e. to render negligible, oxidation ingasoline and in rubber. Most of such anti-oxidants, such as para-amino phenol, alpha naphthalamine, phenyl beta naphthalamine,

benzoylamino phenol, diphenylamino ethane and the aldehyde amine reaction products are relatively ineffective in preventing discoloration of indene polymers. Whereas they serve to retard color development, they do not prevent the resin from obtaining ultimately a color depth almost equal to that reached when anti-oxidants are absent.

I have discovered, however, that the inclusion with indene polymers of a small quantity of a particular class of anti-oxidants is efiective to prevent color development in the indene polymers. This class of anti-oxidants consists of the alkyl polyhydroxy spiro hydroindenes, or in the preferred nomenclature of Chemical Abstracts of the American Chemical Society, the alkyl polyhydroxy splro indanes. Such compounds are characterized by more or less complex structure presenting unsaturated ring nuclei with hydroxyls, and saturated ring structure joining the unsaturated nuclei. These compounds and the methods invloved in their preparation are described in various publications, among which are a paper by Fabrinyl and Szeky, Berichte der Deutchen chemischem Gesellschaft, vol. 38, page ,large amount of Water.

4,5,6,4,5',6' hexahydroxy 1,1 spiro bis-indane;

3,3,3,3',5,6,7,5,6',7 hexahydroxy 1,1 spiro bisindane; 3,3,3',3' tetramethyl 5,5 dihydroxy 6,6,

dimethoxy 1,1 spiro bis-indane; 3,3,3',3 tetramethyl 5,5 dimethoxy 6,6 dihydroxy 1,1 spiro bis-indane; 3,3 dimethyl 3,3 diethyl5,6 diethoxy I ',6 dihydroxy 1,1 spiro bis-indane.

The formula for 3,3,3,3' tetramethyl 5,6,5',6' tetrahydroxy 1,1 spiro bis-indane may be taken as representative. The currently accepted and apparently sound formula for that substance may be given as follows:

The melting point of the above compound is 7 from 280 C. to 285" (3., with some attendant de-,

composition. Like all the alkyl polyhydroxy indanes, it is soluble in acetone and other ketones, sparingly soluble in low boiling aliphatic solvents, and insoluble in water.

As described in the articles to which reference has been made above, the alkyl polyhydroxy spiro indanes are best prepared by condensing polyhydroxy phenols with ketones in an acid medium, such as an acetic acid-hydrochloric acid mixture. The desired compounds are insoluble in such a medium, and are precipitated as condensation proceeds. The alkyl polyhydroxy indanes for preventing color development in indene resin may be prepared by condensing such phenols as catechol, pyro-gallol, phloroglucinol, quinol, and 1,2,4 trihydroxy benzene with such ketones as acetone, methyl-ethyl ketone, methyl-propyl ketone, and ethyl-propyl ketone. If the ketones of higher molecular weight be used, a lesser yield of condensate is had, but such ketones are usable.

I have discovered further that suphonation products of the alkyl polyhydroxy indanes, and boric acid salts of the alkyl polyhydroxy spiro in= danes are similarly effective to prevent color development in indene resin.

As exemplary of sulphonation of the alkyl polyhydroxy spiro indanes, I shall take a tetramethy15,5,6,6' tetrahydroxy 1,1 spiro bis-indane. One part by weight of that material was added to 3 parts by weight of 65% oleum (65% S03 and H2804) at 0 0., and was agitated for complete solution therein. Agitation was continued until a small sample, taken out, was soluble in a. The reaction product Was poured into water and was neutralizedwithcalcium hydroxide. V a

The mixture was filtered and the filtrate was precipitatedby treatment with sodium carbonate until no further precipitation took place. The precipitate was filtered out, and was evaporated. under vacuum to obtain the sodium sulphonate of the spiro indane. It is not certain that sulphonation takes place at all four positions 417,437, but the following formula for the sulphonated indane is theoretically possible:

I prepare, also, for use as an anti-oxidant preventing the discoloration of indene resin, the metallic or organic base salts of an acid-reacting complex formed by reacting an alkyl polyhydroxy spiro indane with boric acid. The preparation of such alkyl polyhydroxy spiro indane-boric acid salts is exemplified by the following:

An alkyl polyhydroxy spiro indane and an organic base, such as diphenylguanidine are dissolved in equal molecular proportions in acetone with warming. Boric acid is added to the solution in molecular equivalency with the spiro indane, and the mass is warmed. The solid material which is formed is digested with warm water and is filtered. The material thus formed is a fairly;

stable spiro indane-boric acid salt. This salt is particularly desirable for use in compositions which contain an acid substance with the indene" resin. This is because the presence of an acid tends to lessen the effectiveness of the alkyl polyhydroxy spiro indanes in preventing discoloration of the indene resin, and the boric acid salt of the spiro indane is more capable of resisting the effect of the acid.

To prevent yellowing of the indene resin, I include with the indene polymers of the resin from about 0.05% by weight of an alkyl polyhydroxy spiro indane material selected from the alkyl polyhydroxy spiro indanes, the sulphonated alkyl polyhydroxy spiro indanes, and the alkyl polyhydroxy indane-boric acid salts. Quantities up to and even in excess of 5% of the substances do not' tend to detract from the coherence and other film-forming properties of the resin. It is a fact that the alkyl polyhydroxyspiro indanes are not highly soluble; and that from 3% to 5% is the greatest proportion of them that will remain associated with the polymers of the resin Without precipitation from evaporative solvents or incompatibility With non-volatile plasticizers for the indene resin. In most instances, as has been noted, a small quantity of the alkyl polyhydroxy spiro indane materials is adequate to prevent yellowing of an indene resin with the polymers of which it is associated. For some purposes, however, alkyl polyhydroxy spiro indanes in excess of 5% the Weight of the indene polymers usefully may be associated with them as a minor content of the non-yellowingindene resin.

With a very pure low molecular weight indene resin in solution in a'solvent such as mineral spirits, from 0.1% to 0.3% of the spiro indane itself usually is adequate. If however, the resin should have a perceptible content of phenols, or other acidiccontent, from-0.1% to 0.3% of the boric acid salt of a spiro indaneor. at least 0.4%

or 0.5% of the spiro indane itself should be included in the solution. If a solution is to be made of a high molecular weight indene resin insoluble in mineral spirits (which is of high purity) and dissolved in a suitable solvent such as h flash solvent naphtha, from 0.05% to 0.2% of the spiro indane itself usually is adequate. In the case of a plastic composition composed of indene resin, plasticizing materials and fillers in which one or more of the components additional to the indene resin is acidic, from 0.3% to 1.00% of a boric acid salt of the spiro indane desirably is included, and the inclusion of 0.9% or 1.00% of the spiro indane itself is indicated.

If a sulphonated alkyl polyhydroxy spiro indane is used, the proportions of that material desirably included follow very closely the proportions given for the spiro indane itself.

In all the foregoing the proportions of the spiro indane materials are based upon parts by weight or" the indene polymers is the solution or composition. Customarily the indene resin is made up for sale and use as a solution or composition, and in the case of a solution, the spiro indane material is associated with the indene resin in the solution. If it is desired, after including the spiro indane material, to distill off the solvent and thus to obtain a solid indene resin including the spiro indane, it is desirable to include a substantially greater quantity of the spiro indane material, such as from 2 to 4 times the proportional quantities given above, in order that the prescribed proportion of the spiro indane material will be included in the solid indene resin. This is because there is some loss of the spiro indane material during distillation. It appears, however, that the spiro indane material is effective to prevent discoloration of the indene resin when used either by associating it with the indene polymers in solution, by associating it with the indene polymers in a solid or semi-solid composition, or by associating it with the polymers of a solid indene resin.

The following examples illustrate the principles of my invention:

Example No. 1

. A light-colored commercially pure (about 97% pure) indene resin of low molecular weight melting about 78 C. (ball and ring) was dissolved in an equal weight of mineral spirits. A tetramethyl tetrahydroxy spiro indane in a quantity equal to 0.3% the weight of the indene resin was dissolved in acetone and was added to the resin solution. The acetone solution of the spiro indane included a small quantity of the mono-ethyl ether of ethylene glycol, in order to prevent precipitation of the spiro indane. The spiro indane was mixed thoroughly with the indene resin solution.

The solution so formed was adapted to filmformation by evaporation of the solvent to leave a film of indene resin. Upon formation of such film by evaporation in air, and upon re-dissolution and analysis of the resin forming the film, it was found that most of the spiro indane remained with the resin in the film, there being but slight loss of that material during the course of normal evaporation.

A film of the deposited resin when exposed to ultraviolet light in a Weathermeter for 24 hours gave no indication of discoloration. Similarly exposure to sunlight for three weeks left the film still wholly free from discoloration. A film of an identical resin solution, but containing none of the spiro indane, gave a perceptibl indication of discoloration when exposed to bright sunlight for 12 hours.

It should be borne in mind with respect to the yellowing tendency of indene resin that it is the coumarone content of coumarone-indene resin which is most strikingly susceptible to yellowing. A pure indene resin does possess avery definite tendency toward discoloration on exposure to sunlight, but that tendency develops more slowly and does not proceed so far as in coumarone-indene resin. The effect of the spiro bisindane in inhibiting discoloration of indene resin is correspondingly more positive than in the case of coumarone-indene resin.

Example N0. 2

A light-colored high molecular weight commercially pure (about 97% pure) indene resin melting about C. (ball and ring) was dissolved in an equal weight of high flash (coal tar) solvent naphtha. A diethoxy-dihydroxy-dimethyl-diethyl spiro indane was added in acetone solution in a quantity equal to 0.15% the weight of the indene polymers in solution. The spiro indane was mixed thoroughly with the indene resin solution.

A film of resin deposited from the solution by evaporation of the solvent in air showed no tendency to discolor when exposed to ultra-violet light in a Weathermeter for 24 hours. Similarly a film of the resin showed no tendency to discolor upon exposure to sunlight for a period of three weeks.

Example N0. 3

A light-colored commercially pure (about 97% pure) indene resin of low molecular weight meltingabout 60 C. (ball and ring) was dissolved in one-third its weight of mineral spirits, and an emulsion was formed by agitation with a small amount of triethanolamine-oleic acid soap. There was agitated with this emulsion tetrahydroxy tetramethyl spiro indane sodium sulphonate in a quantity equal to 0.2% the weight of the indene polymers in the solution. The emulsion was diluted with an equal volume of water and was allowed to stand in a bottle exposed to sunlight.

After a period of three weeks no discoloration was detectable.

Example No. 4

-A plastic composition was made up composed 25 parts by weight of low molecular weight commercially pure (about 97% pure) indene resin melting about 60 0. (ball and ring), 25 parts by weight blown soya bean oil, and 50 parts by weight of precipitated calcium carbonate. To this composition there was added tetrahydroxy tetramethyl spiro indane borate (urea salt) in a quantity equal to 0.4% the weight of the indene resin in the composition. The mass was mixed well, was plastered on a slide, and was exposed to sunlight. After an exposure of thirty days, no tendeny toward discoloration could be observed.

Example No. 5

To the same plastic composition as in Example No. 4, there was added 1.0% of tetramethyl tetrahydroxy spiro indane. As in Example No. 4, the mass was mixed Well, was plastered on a slide, and was exposed to sunlight. After exposure to sunlight for thirty days, a barely perceptible tendency toward discoloration was observed.

weight, melting about 78C. (ball and ring), was

dissolved in an equal weight of mineral spirits. A tetram'ethyl tetrahydroxy spire indane in a quantity equal to 0.6% the weight or theindene resin was dissolved in acetone and. was added to the: resin solution: The acetone solution of. the

spiro indane included a small quantity of the mono ethylether of ethylene glycol, in order to prevent. precipitation of the spiro indane. The spiro indane wasmixed thoroughly with'the indene resin solution. I j i The solution so formed was subjected'to distillation with steam, care being taken to utilize a temperature no greater than required to distill of: the solvent. The solid indene resin was recovered;

-Upon analysis the solid indene resinwas found to contain about 0.3% of the spiro indane. Upon reediss'olution in mineral spirits, and upon deposition of the resin in a film, the film was found to possess the same resistance to yellowing that was possessed by the film deposited from the solution of indene polymers in association with the spin) indane made in accordance with the procedure Of Example No. 1. That is, no tendency toward discoloration was observed following either exposure to ultra-violet light in a Weather-'- meter for 24' hours, or following exposureto surllight for'three weeks.

Example 2V0. 7

A light-colored commercially pure (about 97% pure) indene resin of high molecular weight melting about 145 C. (ball and ring) was fused. With this fused resin there was mixed tetramethyl. tetrahydroxy spiro indane in a quantity equal to 0.6%- the weight of the resin. parts by weight of the resin were worked up with 20 parts by weight of dibutyl phthalate and 30 parts by weight of white (titanium oxide)" pigment. The

mass thus formed when exposed to ultra-violet light in a Weathermeter for 48 hours showedno tendency toward discoloration. 7

Example No. 8

A low molecular weight commercially pure (about 97% pure) indene resin melting about C. (ball and ring) was fused, and tetramethyl tetrahydroxy spiro indane borate in a quantity equal to 0.4% the weight of indene resin was worked thoroughly into the body of the resin.

8 It is correct to say any member of the group consisting of the alkyl polyhydroxy spire indane materials above disclosed. namely the alkyl polyhydroxy spiroindanes themselves-,the sulphonated alkyl polyhydroxy spiro 'indanes, and the boric acid salts of the alkyl polyhydroxy spiro indanes, when associated with the polymers of indene resin preventyellowing of the resin. That is, they not only greatly retard yellowing. but pre vent permanently what maybe considered the normal color development of each individual indene resin. It is to be understodtha't the foregoing examples are exemplary only of the ways in which the specifiedspiro indanes can be as-- sociated effectively with the polymers or indene resin.

Where proportions may have been stated without qualification throughout the foregoing specification, such proportions are to be taken" as in parts by weight, and where throughout the speci fication melting point of resins has been given without qualification, that melting point is to be taken as by the ball and ring method of melting point determinationfor resins.

I claim as my invention: 1

l. A non-yellowing indene resin composition consisting of indene polymers and an alkyl polyhydroxy spiro indane material selected from the group consisting of the alkyl polyhydroxy splro indanes, the sulphonated alkyl polyhydroxy spiro' indanesand the boric acid salts of the alkyl polyhydroxy spiro indanes', the said alkylpolyhydroxy spiro indane material being present in a quantity approximately equal to from 0.05% to 5.00% the weight of the indene'polymers.

2. A non-yellowing indene resin' composition consisting of indene polymers and an alkyl polyhydroxy spiro indanein a quantity approximately equal to from 0.05% to 5.00 the Weight of the REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS- Number' Name Date 2,176,881 Burroughs Oct. 24, 1939 2,176,882 Fisher Oct. 24, 1939 2176,883 Fisher Oct. 24, 1939 2,266,675 Carmody Dec. 16, 1941 

